Electrical heating unit and method of making the same.



W. A. CARTER & S. CROCKER. ELECTRICAL HEATING UNIT AND METHOD OF MAKING THE SAME.

APPLICATION FILED JUNE 5.1916

Patented Julv 10, 1917 2 SHEETSSHEET1 w. A.CARTER-& s. CROCKER. ELECIRICAL HEATING UNIT AND METHOD OF MAKING THE SAME.

APlfLlCATION FILED JUNE 5.1916.

Patented July 10, 1917.

2 SHEETSSHEET 2 wuc/wto'zs IVZ'Zber/i, Curie) Sabin Crvc 3'6) UNITED srATEs PATENT onnrcn.

WILBEB A. CARTER AND SABIN CROCKER, OF DETROIT, MICHIGAN, ASSIGNORS TO I GENEBAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

ELECTRICAL HEATING METHOD OF MAKING THE SAME.

Specification of Letters Patent. Patented J l 191% Application filed June 5, 1916. Serial No'. 101,771.

To all whom it may concern.

Be it known that we, WI'LBER A. CARTER and SABIN OROCKER, both citizens of the United States of America, residing at Detroit, in thecounty of Wayne and State of Michigan, have invented certain new and useful Improvements in Electrical Heating Units and Methods of Making the Same, of which the following is a specification, reference being had therein to the accompanying drawings. 7

The invention relates to electrical heaters and the method of making the same,'and the heaters embodyingmy invention are more particularly designed for the heating of ovens to relatively low temperatures and Where it is important to limit the temperature of the resistor element, but also applicable to other uses. One important use of such heaters is in the heating of ovens used .for drying enamels and varnished articles, where highly-inflammable vapors are drlven ofi; for if any portion of the heating element attains the ignition temperature of the gases an explosion will occur. Under the limitations just described,the resistor element must necessarily be provided with an extensive heat-radiating surface in order to develop sufiicient heat for the entire oven without itself exceeding the temperature limit. It is also important to arrange the heater compactly, so as not to limit the capacity of the oven for receiving the work. To accomplish this result, we have devised a construc- 35 tion of resistor having a large heat-dissipating surface arranged Within a relatively small area, without danger of short circuiting or exceeding the temperature limit in any portion thereof. In the drawings:

Figure 1 is a side elevation of a mounted resistor of our improved construction;

Fig. 2 is a sectional perspective view of a portion thereof;

Fig. 3 is a cross section on line H Fig. 1; and

Fig. 4 is an elevation of a sheet metal blank from'which the resistor is formed.

Our improved resistor is preferably formed from sheet metal and preferably from sheet iron or steel, as this has-the double advantage of relatively high specific resistance and relatively great mechanical strength and rigidity. To secure the required amount ofsurface-within given space limits, the metal avoid by so fashioning the sheet-metal as to brace the same transversely of the plane thereof. We have also provided a mounting which holds the parallel portions in properly spaced relation.

Specifically, A is a sheet metal blank, which is slitted or cut transversely alternately from opposite sides thereof, to form a zigzag construction, having a series of parallel portions B B, etc. Each of these portions B B, etc., is stiifened, preferably by pressing thereinto one or more longitudinally-extending beads C. The portions D, which form the connections between adjacent portions B B, etc, are returnbent oppositely at opposite ends, so that said portions B B, etc, are arranged in parallel planes. E are insulator supporting strips,

which are provided with a series of parallel slits extending inward from one edge thereof, into which the portionsB B, etc, are inserted, while the shoulders F formed by the returnbent portions D at the upper end of the resistor are adapted to rest upon the side of the strip. G and H are suitable clips for securing the resistor to the strips E.

With the construction as described, the heating unit may be suitably mounted either adjacent to the side walls or the top or bottom of the oven. When in operation, the relatively large amount of exposed surface will rapidly dissipate the heat by both radiation and convection, thereby limiting the temperature rise inv the resistor itself and also rapidly heating the air and surrounding objects. The cross-section is maintained sive parallel strips or ribbons connected at form a series of portions arranged in parallel planes and spaced from each other by less than the width thereof, said portions being longitudinally beaded to brace and stiffen the same and being connected to each other by returnbent portions alternately at .opposite ends thereof, a support for said resistor, comprising a plurality of insulator bars slitted to receive said parallel. portions of the resistor, and clips for holding the resistor to said bars.

3. In an electrical heating unit, a resistor comprising a sheet-metal blank fashioned to Y form a series of portions arranged in parallel planes, said portions having returnbent transversely extendin portions alternately arranged at opposite ends thereof and forming overhanging shoulders, and an insulator strip engaging the edges of said portions in parallel planes and the shoulders formed by said returnbent portions.

4. In anelectrical heater, a resistor formed of sheet-metal cut to form zigzag portions, being bent to arrange the latter in substantially parallel planes extending transversely of the original plane thereof, and means for maintaining said parallel portions in spaced relation.

5. In an electrical heater, a resistor formed of sheet-metal cut to form zigzag portions in the plane of the sheet, being bent to arrange the latter in substantially parallel planes transverse to the general plane of the resistor.

6. In an electrical heater, a resistor formed from a sheet-metal blank, fashioned to form a series of spaced portions in parallel planes with return-bent portions connecting the same adjacent to the alternate opposite ends thereof, and at opposite sides,

and means for maintaining said parallelportions in spaced relation.

7. In an electrical heater, a resistor formed from a sheet-metal blank, fashioned to form a series of portions in parallel planes spaced from each other by less than the width thereof, with return-bent portions connecting the same adjacent to the alternate oppositeends thereof and at opposite sides, said portions being beaded to brace the same.

8. An electrical heater, comprising a resistor formed from sheet-metal, fashioned to form a series of sections arranged in par allel planes and spaced from each other by less than the width thereof, said sections being longitudinally headed to brace and stifl'en the same and connected by returnbent portions alternatelyat opposite ends thereof and at opposite sides, and a support for said resistor comprising an insulator having parallel slits therein for receiving said parallel sections.

9. In an electrical heating unit, a resistor, formed of sheet-metal blank, fashioned to form a series of portions arranged in parallel planes, said portions being longitudinally beaded to brace and stiflen the same and having return-bent connecting ortions alternately arranged at opposite en s thereof and on opposite sides.

In testimony whereof we afiix our signatures.

W. A. CARTER. SABIN (JROCKER. 

